An ambitious idea that Rapport has already tried in a blitz game. White prepares to castle queenside.
9... c8e6  10. b1a3 This is the idea behind ​​White's play. The knight finds a good square on b5. 10... b8c6  11. a3b5  11... d6b8 Keeping the bishop is important because it protects the center. Eventually, Black can develop the rook on a6.